Laparoscopic surgery has become common for minimally-invasive procedures. Laparoscopic surgery involves making a small number of small incisions, inserting surgical tools and a laparoscopic vision device having a light source and imaging apparatus through these openings to a surgical site, and then performing surgery within a body cavity. The body cavity is often enlarged by administering gas, such as carbon dioxide, to give the surgeon a larger, more exposed field of view. The surgical tools are typically manipulated directly by the surgeon or indirectly through a robotic-coupled apparatus that articulates based on how a surgeon manipulates a set of “joysticks”. Laparoscopic surgery (both manual and robot-assisted) is particularly common for abdominal and pelvic procedures, including cholecystectomy and radical prostatectomy.
Similarly, endoscopic surgery has also become common for minimally-invasive surgical procedures in body cavities that communicate outside the body through a body opening. Endoscopic surgery involves threading an endoscope through the opening to a surgical site. The endoscope is a flexible device equipped with a light source and imaging apparatus, and typically having a lumen through which a gas, such as carbon dioxide, can be admitted to inflate the cavity to enable improved vision and through which a surgical tool may be threaded. Typically, an endoscope has manipulation or steering wires running from its head to a handle attached to its base so that the endoscope tip may be twisted or straightened by moving knobs on the handle. This allows threading of the endoscope through the body opening to the surgical site. Once the endoscope is threaded to the surgical site, surgical tools are threaded through the lumen of the endoscope and manipulated to perform the desired surgical procedure. The surgeon uses images obtained by the imaging apparatus of the endoscope to verify correct placement of the surgical tools, and to guide the surgery. Endoscopic surgery is often used for polypectomy in the colon, as well as transurethral prostatectomy and transurethral removal of bladder tumors (TURBT). Endoscopes are also often used for biopsies, including biopsies of the lung, colon, esophagus, and stomach. Endoscopes may be used for many other procedures than those listed here.
In typical laparoscopic and endoscopic procedures, a surgeon views the surgical site using the light source and optical imaging apparatus, and performs surgery under direction of images acquired by the imaging apparatus. The imaging apparatus used for the majority of endoscopic and laparoscopic procedures provides the surgeon with two-dimensional images of the surgical site. Recent robot-assisted systems have provided surgeon with a three-dimensional view of the surgical site through stereovision imaging devices. Since surgery is typically directed in accordance with optical images, it is desirable to have good contrast in the images between lesions or tissue needing removal and normal tissue of the subject that the surgeon intends to leave intact. While some tissues, like the gall bladder, have sharp color contrast relative to other nearby tissues, such as normal liver tissue, many other lesions and tumors have little color contrast relative to nearby tissues. Additionally, tissue surfaces are often difficult to visualize in images due to blood and other substances coating the surface.
In addition to contrast between normal and lesion tissue, it can be desirable to resolve differing types of normal tissues so that anatomy can be confirmed, or critical structures, such as nerves and blood vessels, can be left undamaged during the procedure.